EVALUATING THE EFFICIENCY AND SENSITIVITY OF ONE-STEP ... · detection of latent fingerprints is...

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EVALUATING THE EFFICIENCY AND SENSITIVITY OF ONE-STEP

CYANOACRYLATE FUMING METHODS IN THE DETECTION AND

VISUALISATION OF LATENT FINGERPRINTS ON THE ADHESIVE SIDE

OF TAPE

By

Krystal Van Der Spil

Thesis submitted in the fulfilment of the requirements for the degree of

Master of Forensic Science (Professional Practice)

in

The School of Veterinary and Life Sciences

Murdoch University

Supervisors:

Dr. John Coumbaros (Murdoch University)

Dr. Carolyn McLaren (AFP)

Elliot Cottrill (WAPol)

Semester 1, 2019

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DECLARATION

I declare that this manuscript does not contain any material submitted previously for the

award of any other degree or diploma at any university or other tertiary institution.

Furthermore, to the best of my knowledge, it does not contain any material previously

published or written by another individual, except where due references have been made in

the text. Finally, I declare that all reported experimentations performed in this research

were carried out by myself, except that any contribution by others, with whom I have

worked is explicitly acknowledged.

Signed: Krystal Van Der Spil

28/06/2019

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Acknowledgements

Firstly, I would like to thank my supervisor, Dr. John Coumbaros, for your constant guidance

and feedback towards my project. You never once doubted me, and I am so grateful for

your continuous support throughout this experience.

To Dr. Carolyn McLaren and Elliot Cottrill; thank you for offering your assistance and

providing me a basis for my research. I appreciate your interest and input despite your busy

schedules.

To my family, friends, and fellow Masters peers; I appreciate every one of you. Not only

have you continuously encouraged me to be the best I can be, but you have also

contributed to making this journey memorable, and I could not have done this without you.

1

Table of Contents

Title Page .................................................................................................................................. i

Declaration .............................................................................................................................. ii

Acknowledgements ................................................................................................................ iii

Part One

Literature Review ............................................................................................................... 3-45

Part Two

Manuscript ....................................................................................................................... 47-90

2

Blank Page — not numbered

3

Part One

Literature Review




OF TAPE

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Abstract

The evidential value of adhesive tape recovered from a crime scene plays a critical role in

the criminal investigation as it could potentially contain things such as fibres, hair, DNA

evidence, or fingerprints. Adhesive tape is a ubiquitous material that can be used in crimes

that involve kidnapping and murder, as well as used to house cables in acts of terrorism.

With regards to the adhesive side of tape, the sticky nature of this surface not only increases

the likelihood of latent fingerprint deposits but has routinely proved to be a problematic

substrate to work with. As latent fingerprints are generally invisible to the eye,

enhancement methods are required to conduct adequate analysis on the fingerprint details.

Despite several methods of fingerprint enhancement available, common issues including

high background staining and low selectivity of fingerprint deposits create a difficult

problem for forensic investigators to solve. Studies have shown that these issues can be

overcome by utilising aqueous solutions of fingerprint powders, as well as traditional dye

methods like gentian violet. Fluorescent dyes have also been explored and shown to be very

effective when used on darker-coloured adhesive tapes. With regards to aged latent

fingerprints, sticky-side powder and phase transfer catalysts have proven to be viable

methods of detection and development. Traditional cyanoacrylate fuming was observed to

be the best method of development in all reviewed cases, but the requirement of

subsequent dye staining poses potential health issues to the user and the environment.

One-step cyanoacrylate fuming has been proposed as a method incorporating the staining

step into the cyanoacrylate fuming step, thus completing both steps simultaneously. As one-

step cyanoacrylate fuming is a relatively new method of development, its potential

application to the development of latent fingerprints on the adhesive side of tape has not

been explored to its full extent and should be researched more extensively.

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Table of Contents

Abstract ............................................................................................................................ 4

LIST OF FIGURES ............................................................................................................... 7

LIST OF TABLES ................................................................................................................. 7

LIST OF ABBREVIATIONS ................................................................................................... 8

1. Introduction ................................................................................................................. 9

2. Discussion ................................................................................................................... 12

2.1. Fingerprint Background 12

2.1.1 Friction Ridge Skin Development .......................................................... 12

2.1.2 Ridge Characteristics and Patterns ....................................................... 13

2.1.3 Latent fingerprint Composition............................................................. 15

2.2 Adhesive Tape Background 17

2.2.1 Brief History .......................................................................................... 17

2.2.2 Adhesive Tape Composition ................................................................. 18

2.3 Enhancement Techniques 20

2.3.1 Powder/Particle Suspensions ............................................................... 20

2.3.1.1 Sticky-side Powder ................................................................. 20

2.3.1.2 Black Powder Suspension.. .................................................... 21

2.3.1.3 White Powder Suspension ..................................................... 22

2.3.1.4 Physical Developer ................................................................. 23

2.3.1.5 Small Particle Reagent ........................................................... 24

2.3.1.6 Cadmium-selenide Nanoparticle Suspension ......................... 24

2.3.2 Dye Methods ........................................................................................ 25

2.3.2.1 Gentian Violet ........................................................................ 25

2.3.2.2 Ardrox and Liqui-Drox ............................................................ 26

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2.3.2.3 Novel Fluorescent Dyes; HB-7, HB-9, HB-11 ........................... 27

2.3.2.4 Phase Transfer Catalyst ......................................................... 27

2.3.3 Cyanoacrylate Fuming .......................................................................... 28

2.3.4 One-Step Cyanoacrylate Fuming .......................................................... 29

2.4 Comparison of Enhancement Techniques 31

3. Experimental Aims and Objectives .............................................................................. 35

4. Conclusion .............................................................................................................. .... 36

5. References .................................................................................................................. 38

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LIST OF FIGURES

Figure 1 Structural characteristics of friction ridge skin .............................................. 12

Figure 2 The three main fingerprint classes from left to right; loop, whorl, and arch. 14

Figure 3 Fingerprint sub-classes. A) Right Loop; B) Left Loop; C) Plain Whorl; D) Central

Pocket Loop Whorl; E) Double Loop Whorl; F) Accidental Loop Whorl; G) Plain

Arch; H) Tented Arch...................................................................................... 14

Figure 4 Most common types of minutiae observed in a fingerprint .......................... 15

Figure 5 Image displaying the presence of pores along the friction ridge skin............ 15

LIST OF TABLES

Table 1 Chemical components of glandular secretions.............................................. 17

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LIST OF ABBREVIATIONS

BPS Black Powder Suspension

BY40/BR28 Basic Yellow-40/Basic Red-28

CA Cyanoacrylate

CdSe Cadmium-selenide

FRS Friction Ridge Skin

GV-E Gentian Violet in Ethanol

GV-P Gentian Violet in Ethanol + Phenol

PTC Phase Transfer Catalyst

R6G Rhodamine 6G

RAY Rhodamine 6G/Ardrox/Basic Yellow-40

SPR Small Particle Reagent

TiO2 Titanium Dioxide

UV Ultraviolet

WPS White Powder Suspension

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1. INTRODUCTION

Fingerprints are one of the most discriminatory types of evidence encountered at a crime

scene.1 Since 221 B.C. fingerprints have been used as a means of identification and its

current use to aid criminal investigations is still proven to be an invaluable tool.1

Fingerprints recovered from a crime scene play a significant role in the three aspects of

forensic investigations; demonstration of whether a crime had been committed,

identification of the individuals involved and their association to each other, and assisting in

reconstruction of the sequence of events.1, 2 The evidential value of a fingerprint enables the

identification of an individual based on the papillary ridge patterns present on the pads of

the fingers.3, 4 Latent fingerprints, specifically, can be deposited onto a range of substrates,

which ultimately denotes the method of enhancement, be it optical, physical or chemical.5

Crimes such as kidnapping, terrorism, rape, and murder often involve the use of adhesive

tape, which frequently presents latent fingerprints on the adhesive side.6, 7 Due to its sticky

nature, and difficulties in handling while wearing gloves, preferred handling is carried out by

bare hands, which significantly increases the likelihood of latent fingerprint deposition.4 As

the development of latent fingerprints generally relies on the interaction between the

chemical residue of the fingerprint and the method of enhancement, the adhesive

properties of tape need to be taken into consideration when choosing an appropriate

development method.8

The general process of developing latent fingerprints, or any evidential fingerprint, always

begins with the least destructive method of analysis, so as to preserve any potential detail

that may be recovered from the print.5 In addition to this, by using the least destructive

method first, it allows for subsequent analysis if needed. An analysis is done using three

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detection methods; optical, physical or chemical.1 Optical or visual detection involves simple

observation and photography of the fingerprint, sometimes accompanied by the use of

white light.9 This detection method is generally non-destructive, but if exposed to high-

powered lasers, which utilises lights of extreme intensities, the process can be harmful.10

Optical detection is always carried out before physical or chemical examination as these

methods are commonly destructive.1 The use of physical or chemical enhancements for the

detection of latent fingerprints is strongly dependent on the substrate that the fingerprint is

deposited onto.

Some porous substrates, like fabrics, paper, or wood, can absorb the fingerprint deposits,

thus changing the composition.9 Additionally, these surfaces can absorb and react with the

physical or chemical method of development applied, causing high background staining and

issues in the visualisation of the print.11 Processes, such as physical developer and Ninhydrin

have been found successful for the use on porous surfaces.12, 13 Non-porous substrates tend

to be easier to develop latent fingerprints on as there is less interference from the

background; however, fingerprints deposited onto these surfaces tend to be more fragile,

thus requiring them to be preserved as soon as possible.14 Physical development methods

for use on non-porous substrates include fingerprint powders, such as fluorescent powders

and carbon black, whereas chemical methods include vacuum metal deposition or

cyanoacrylate (CA) fuming. Though most substrates can be classed into porous or non-

porous, there are some surfaces that do not fall under these categories, such as waxy

surfaces or adhesive tape.

While adhesive tape is a potential type of physical evidence recovered from a crime scene,

the sticky nature of the adhesive side proves to be problematic with current methods of

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latent fingerprint development.15 As a result of its adhesive properties, the sticky side of

tape increases the likelihood of a fingerprint to be deposited.4 Various studies have been

conducted in order to create a method that will effectively develop latent fingerprints on

this problematic surface, but as there are multiple brands, colours and compositions of

adhesive tape, there has been no single technique suitable for all cases.16

CA fuming has previously been found to be one of the most successful practices in

developing latent fingerprints on the adhesive side of tape, but requires additional dye steps

for fingerprints on dark surfaces.17 This extra step is not only time consuming, but can also

present carcinogenic properties as a result of using the dyes.18 An alternative method,

proposed as the one-step CA fuming method, incorporates a fluorescent powder into the CA

fuming process, primarily developing and staining the fingerprint in one step.19 Currently,

various brands of one-step CA fuming have become commercially available, but limited

research has been performed to evaluate their use for developing latent fingerprints on the

adhesive side of tape.

This literature review focuses on evaluating the current methods of latent fingerprint

development for use on the adhesive side of tape and, by doing so, aims to assist in

determining whether one-step CA fuming may prove to be a more effective and versatile

method of enhancement for these surfaces. In order to comprehensively understand the

interaction between fingerprint, substrate, and method of development, background

information on fingerprints and the nature of adhesive tape will be included in this review

as these properties vastly affect the choice of development procedures utilised.

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2. DISCUSSION

2.1 Fingerprint Background

2.1.1 Friction Ridge Skin Development

The general anatomy of the skin is what forms the underlying fundamentals of the

examination process of fingerprints. Human skin, comprising of three anatomical layers, is

responsible for several tasks, including temperature regulation and excretion.20 The

outermost layer, the epidermis, forms the protective barrier of the body and is home to the

friction ridge skin (FRS), consisting of ridges and furrows, on the fingers, palms, feet, and

toes.21 FRS is formed due to the papillae at around the 10th week of the gestation period

and remains unchanged throughout life.22, 23 Despite the continuous sloughing of cells on

the surface, from everyday activities, the structural features of the FRS is maintained as a

result of several levels of attachment within the epidermis.1 These attachment levels involve

cell-to-cell interaction between keratinocytes throughout the layers of the epidermis, which

are anchored in position by the interwoven epidermal basal cells and the dermis, creating a

fibrous sheet of cells, locking the epidermis to the dermis.1 Primary and secondary ridges,

formed at the intersection of the dermis and epidermis, code for the fingerprint pattern

visible on the surface of the skin (Figure 1).22

Figure 1 Structural characteristics of friction ridge skin.1

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Due to this intricate attachment, alteration of the FRS is only possible if the basal

keratinocyte template is altered, as a result of ageing, trauma and scars.1, 3, 24

2.1.2 Ridge Characteristics and Patterns

The ridge characteristics of a fingerprint are unique to an individual and are analysed in

three levels of detail; the general fingerprint class, the changing flow patterns of ridges and

the characteristics of individual ridges. Defining a fingerprint's class relies on the use of

singularities, such as cores and deltas. The core is the most central region of the overall

pattern where the direction of the inner-most ridge pivots, whereas the delta is the area

where two ridges diverge after previously running parallel.23 Fingerprints can be segregated

into one of three classes; loops, whorls, and arches. Loop patterns consist of a central core

that curves toward the left or right and a delta on the opposite side of the ridge flow, while

whorl patterns contain a central core with a delta on either side. Unlike loops and whorls,

arch patterns only contain a core, with no deltas (Figure 2).21, 22 Loops and whorls are the

most predominant patterns observed, occurring in approximately 93.4% of all fingerprints,

and arch patterns being the least common.23 From these three classes, fingerprints can be

further divided into subclasses depending on the flow of ridges that structure the main

fingerprint pattern; Loops can be further divided into radial or ulnar loops, determined by

the ridges flowing more toward the ulnar or radius of the forearm; whorls can fall under

four subclasses of either plain, central pocket loop, double loop or accidental loop whorls;

and arches can be further divided into plain or tented arches depending on the prominence

of the arch (Figure 3).25

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Figure 2 The three main fingerprint classes from left to right; loop, whorl, and arch.23

Figure 3 Fingerprint sub-classes. A) Right Loop; B) Left Loop; C) Plain Whorl; D) Central Pocket Loop Whorl; E) Double Loop Whorl; F) Accidental Loop Whorl; G) Plain Arch; H)

Tented Arch. 23

Though fingerprints are broadly classed into these pattern types, the unique identifiers

come down to the discontinuities within the ridges and the features associated with these

individual ridges.23 Individual ridge patterns, known as minutiae, embody the individuality

of the fingerprint, making them the most discriminating feature used in fingerprint

analysis.23 The two types of minutiae that form the basis of varying ridge patterns are ridge

endings and bifurcations; where a ridge terminates and where a ridge diverges into two,

respectively.23 Other minutiae patterns, such as trifurcations, enclosures, spurs and bridges

are simply a combination or variation of these (Figure 4).26, 27 A general fingerprint will

contain up to 80 minutiae, though fewer will be present in a latent fingerprint due to the

presence and position of pores (Figure 5).1 When analysing the individual characteristics of

ridges, the ridge size, and shape, as well as the location of pores, are the main focus. These

low-level details are not commonly used in fingerprint comparison using automated systems

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due to the need for high-resolution scans but can be used by human experts in their

analysis.28, 29 Despite this, the significance of sweat pores present on the FRS is important as

they are responsible for the composition and deposition of latent fingerprints.

Figure 4 Most common types of minutiae observed in a fingerprint.30

Figure 5 Image displaying the presence of pores along the friction ridge skin.23

2.1.3 Latent Fingerprint Composition

The three possible types of fingerprints encountered at a crime scene are plastic, patent,

and latent. Plastic fingerprints are deposited into a surface, such as gum or fresh paint,

leaving a 3D impression, whereas patent fingerprints are a result of residues from the finger,

such as blood or dirt, depositing onto the substrate.11, 31 Both plastic and patent fingerprints

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are readily visible to the human eye, generally without need for enhancement; however,

latent fingerprints require special visualisation techniques.

Among these three impression types, latent fingerprints are the most common fingerprints

encountered at a crime scene and are a result of excreted chemicals through the pores

present on the FRS.32 When a surface is touched, residue on the pads of the fingers,

comprised of natural secretions, epidermis components, and environmental contaminants,

are deposited.32 Natural secretions from the body are the product of one of the three types

of gland present in the skin; apocrine, sebaceous and eccrine. Apocrine glands are primarily

present in the groin, breasts, and armpits whereas sebaceous glands are present over the

entire body except for the hands and feet.20 The only glands present in the FRS are the

eccrine glands, with 2500—3000 per 2.5cm2 of skin and are the largest glands of this type in

the body.1 Though the two major origins of latent fingerprints are from sebaceous and

eccrine glands, latent eccrine fingerprints are more representative in latent fingerprint

identification because of the eccrine glands present on the FRS.32 Primarily, the major

component of eccrine secretions is water (99.0—99.5%) and a mixture of organic and

inorganic elements; however, in relation to latent fingerprints, activities such as touching

the face or hair can alter the chemical constituents through contamination from sebaceous

gland secretions (Table 1).33

Despite water constituting majority of eccrine sweat production, this does not guarantee

that typical latent fingerprints would reflect the same percentage of water. Water secreted

through eccrine sweat glands is often evaporated or reabsorbed into the skin during

temperature regulation.32 In addition to this, other factors such as age, medication, recent

activities, environmental conditions, and substrate surface can alter the chemical

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composition of a latent fingerprint.24 These various factors need to be taken into

consideration when choosing the appropriate visualisation technique, especially in relation

to techniques that rely on chemical interactions with latent fingerprint components.

Table 1 Chemical components of glandular secretions.34, 35

Secretory Gland Chemical Components

Organic Inorganic

Eccrine

Amino acids Choline Creatinine Lactic Acid Polypeptides Proteins Sugars Urea Uric acid

Ammonia Bicarbonate Chloride Metal ions (Na+, K+, Ca2+) Phosphate Sulphate Water

Sebaceous

Fatty acids (30—40%) Wax esters (20—30%) Glycerides (20—25%) Squalene (10—15%) Sterols (3—4%) Sterol Esters (2—3%)

Apocrine Carbohydrates Proteins Sterols

Iron Water

2.2 Adhesive Tape Background

2.2.1 Brief History

Adhesive tapes have been in common use for over a century. Dating back to the 1900s, the

world's first scotch masking tape was developed as a solution to auto painter difficulties in

creating clean lines between two paint jobs.8 In 1942, during World War II, duct tape was

developed in order to repair weapons and seal ammunition cases.8, 36 Not too long after the

development of duct tape was the creation of clear scotch tape in the 1930s, which is often

used for packaging items.8, 37 Since then, the manufacture of adhesive tapes and their

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multiple uses have evolved and continue to do so. As adhesive tapes are ubiquitous, it is not

uncommon for them to be utilised in the commission of a crime.6 Duct tape is often

recovered from crimes where abduction or murder has occurred, but can occasionally be

retrieved from packages that contain contraband or explosive devices.38 In these cases, the

potential to recover forensic evidence is imperative to aid the investigation. In relation to

forensic analyses of adhesive tapes, complications arise due to the assortment of adhesive

tapes commercially available.16

2.2.2 Adhesive Tape Composition

The composition of adhesive tapes varies with each brand and batch, the manufacturer and

the types of glues used.16 Tapes cannot be adequately compared and analysed using visual

examination, but laboratory methods, such as Fourier-transform infra-red spectroscopy, can

be utilised to distinguish tapes of different sources and compositions.16 Adhesive tape

generally consists of a plastic layer with a glue layer but can also be as complex as to contain

a release coating, a backing film, a primer layer, and an adhesive layer.39, 40 In order to avoid

the adhesive side from sticking to the backing side when rolled, a release coating is

applied.40 Not only does this prevent the adhesive from sticking to the tape beneath it, but it

also reduces the tension that may arise during unrolling.40 The backing film, more commonly

known as the non-adhesive side of tape, can come in a variety of colours as well as a variety

of materials. Duct tape is made using a polyethylene backing, which is traditionally silver,

with a layer of woven cloth for added strength.38 The woven cloth, also known as the 'scrim',

is a mixture comprised of both natural and synthetic fibres.38 In comparison to duct tape,

plastic packaging tape is often developed using a transparent or brown polypropylene and

masking tape uses a polyester film.37, 41 Some adhesive tapes contain a primer layer, which is

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responsible for enhancing the adhesive force between the tape and the substrate.42 Despite

the fact that latent fingerprints can be present on both sides of adhesive tape (non-adhesive

and adhesive) the same method of enhancement often cannot be applied to both sides,

primarily due to the adhesive properties.15 Glues frequently used in the manufacture of

adhesive tapes are pressure-sensitive adhesives, which are either rubber-based (natural or

synthetic) or acrylic-based.16, 37 Generally, pressure-sensitive adhesives are a complex

polymer, or a mixture of both polymer and resin.37 The adhesive layer itself proves to play

the most important role in fingerprint deposition on the adhesive side of tape because it is

this layer that mostly comes into direct contact with the finger.37 Adhesive tapes recovered

from crimes often adhere together or to a substrate, which complicates analysis of the

adhesive side.43 Proposed methods, such as freezing, have been successful in assisting with

separation of the tape but will not be explored in detail for the purpose of this review.

Other studies have been conducted, focusing on developing methods of fingerprint

enhancement on the adhesive side of tape, but with the various types of adhesives available

some tapes have been proven to be problematic in these approaches. For example, it has

been found that development of latent fingerprints on acrylic-based adhesives is likely to

result in high background staining causing poor contrast in visualisation.44 This is an issue in

forensics as it is not always the same type of adhesive tape encountered at every crime

scene.

In order to evaluate existing methods of latent fingerprint development, with regards to the

adhesive side of tapes, the findings of current literature will be compared and contrasted to

establish the issues with each technique, for the purpose of producing an alternative

method.

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2.3 Enhancement Techniques

2.3.1 Powder Suspensions

Fingerprint powders have proven to be successful in enhancing latent fingerprints; however,

a range of surfaces, such as wetted or rough materials, fabrics, and adhesives have limited

suitability with this forensic technique.16 The use of powder suspensions has been successful

in developing latent fingerprints without interference from the adhesive.43 Powder

suspensions are generally a mixture of three components; powder, detergent, and water.5

Before use, it is important to thoroughly mix the suspension, as suspensions left to stand are

inclined to separate the components within the mixture.45 There is no single powder

formulation to accommodate all adhesives and fingerprints as the effectiveness of varying

powder suspensions are dependent on the adhesive structure.16 Due to this, a range of

powder suspensions have been created in an attempt to accommodate the diverse

compositions and colours of adhesive tapes.

2.3.1.1 Sticky-Side Powder

Sticky-side powder, as the name suggests, was developed specifically to develop latent

fingerprints on the adhesive side of tape.1 The sticky-side powder is mixed with water and

the detergent, Kodak Photo-Flo, to facilitate a thick suspension that is applied to the

adhesive surface by painting it on with a brush before rinsing the tape in water.45 The

resulting developed fingerprint is a dark grey colour.6 This method has been found effective

on the majority of adhesive surfaces, though it has limitations in relation to dark surfaces

due to the resulting developed print being grey in colour.6 In a study by Sock et al.6 sticky-

side powder was applied to masking tape, transparent tape, and black electrical tape. Latent

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fingerprints on both transparent and masking tapes were successfully developed but did not

provide enough contrast on black electrical tape, despite being able to develop the prints. In

concurrence to this, Martin46 yielded the same results in relation to developing fingerprints

on black electrical tape due to the dark colouring of the developed print. Alternatively,

Brzozowski et al.44 applied sticky-side powder to various brown and transparent tapes and

achieved good results on tapes with adhesives made with synthetic rubber, however,

produced poor results on adhesives composed from natural rubber.

2.3.1.2 Black Powder Suspension

Black powder suspensions (BPS) work much the same as sticky-side powder, where a

powder is mixed with a detergent and water. The detergent used is typically Liqui-Nox, but

Photo-Flo can be used too.5, 45 The importance of the detergent in the suspension allows for

easy application due to the surfactant reducing the surface tension.45 Particles suspended in

the mixture can be either iron-oxide or carbon-based, depending on the manufacturer of

the product.1 Studies conducted by Bleay et al.47 illustrated that carbon-based BPS were

more successful in developing fingerprints on the adhesive side of tape in comparison with

the iron-oxide version. It was also observed that there was extensive background staining on

the tapes with acrylic-based adhesive, whereas there was no observable background

staining on tapes with rubber-based adhesives. Bailey et al.43 conducted a study observing

whether fingerprints on the adhesive side of duct tape could be recovered and developed

with BPS after separation using a freezing technique. Findings stated that fingerprint detail

was not observable until treated with suspension powder, in which 48% of the fingerprints

developed illustrated numerous minutiae and more complete pattern details. In addition to

this, there was only 12% of fingerprints in which there was no, to limited, visible minutiae.43

22

2.3.1.3 White Powder Suspension

The mixture of titanium dioxide (TiO2) powders in suspension, more commonly known as

white powder suspension (WPS), has provided a successful alternative to black powder

suspensions, with regards to dark coloured adhesive tapes.46 Though there are several

commercial products of this technique available, various studies have found that the

effectiveness varies with suspensions from different companies.16 TiO2 is a non-toxic, very

fine, non-flammable white powder, which has been proven useful in the development of

latent fingerprints on dark surfaces.16, 45 Scheimer et al.45 suggested that the use of TiO2

powder can be a viable substitute to sticky-side powder, in which superior results can be

achieved on black electrical tape. Different compositions of WPS were tested to analyse

which suspension produced the best result on black electrical tape.45 WPS was mixed with

Photo-Flo, Citron detergent, or both, in which the Citron detergent formulation developed

fingerprints slighter better in comparison to the Photo-Flo formulation, but produced

discolouration of the background which impacted the contrast. The fingerprints developed

from these two methods also showed to decrease in quality in relation to weaker deposited

fingerprints. Additionally, this study illustrated that WPS using a mixture of Photo-Flo and

Citron detergents was consistent in developing high-quality fingerprints when compared to

Photo-Flo only and detergent only suspensions. The combined mixture had less background

discolouration and worked consistently on all of the types of black electrical tape tested,

even allowing the observation of third level detail like creases and pores.45 Williams and

Elliot48 agreed with this, with successful results on both duct and dark-coloured electrical

tapes. Furthermore, a study conducted by Brzozowski et al.44 tested the efficiency of the

WPS Wetwop™ and found it to be the most universal and effective method to develop

23

fingerprints on brown and transparent tapes in comparison to other development methods.

Despite these successes, Bleay et al.47 recommend that WPS should not be used on adhesive

tapes, unless in the case of wetted, dark coloured tapes.

2.3.1.4 Physical Developer

Physical developer, also known as silver powder suspension, is an aqueous, silver-based

reagent that develops latent fingerprints by reacting with the components of sebaceous

sweat.13 Essentially, silver(I) ions are reduced to elemental silver that interacts with the fatty

acids present in a latent fingerprint, resulting in a dark grey or black fingerprint.13 Scheimer

et al.45 tested physical developer, much like WPS, where the effectiveness of the developer

was analysed depending on the mixture components. It was found that the Photo-Flo only

solution rarely developed any fingerprints and, where it did, only developed very faint

fingerprints.45 Opposing to this, the detergent only solution demonstrated excessive

background staining on all of the black electrical tapes tested, despite only applying one

coat of the mixture.45 Although Scheimer et al.45 had successes with combining both Photo-

Flo and detergent in the WPS, with regards to silver powder, the results were found to be

the opposite. The developer had extensive background staining as the silver powder

adhered to the adhesive background, which vastly decreased the quality of the developed

fingerprint.45 In contrast, Sodhi and Kaur13 found physical developer to be successful in the

development of fingerprints on adhesive tape, and especially suitable for detecting

fingerprints on porous and wetted surfaces, as it relies on interactions between lipid

components and fatty acids, which are not soluble in water.

24

2.3.1.5 Small Particle Reagent

Despite being much like its powder suspension counterparts, small particle reagent (SPR)

traditionally utilises molybdenum disulfide particles, which results in a grey developed

fingerprint.17 Black charcoal powder and zinc carbonate can also be used in place of

molybdenum disulfide.17 Due to the resultant grey deposit, SPR has been deemed a suitable

method for the use on black or dark-coloured tapes.45 Bumbrah et al.17 determined that the

quality of the latent prints developed varied with the solubility and concentration of

surfactant in the SPR mixture. In conventional SPR, suspension material and surfactant are

the main components.49 The role of the surfactant is to enhance substrate moisture and

reduce any potential surface tension, thus allowing uniform spreading of the reagent.17 This

is particularly important in relation to the quality of developed prints as high concentrations

can increase the likelihood of the developed prints being weak in nature.49

2.3.1.6 Cadmium-selenide Nanoparticle Suspension

The use of nanoparticles in latent fingerprint development has been increasing due to their

versatility, and sensitivity.50 Cadmium-selenide (CdSe) nanoparticle suspensions require the

particles to be stabilized before use.51 Wang et al.50 applied the suspension to yellow sealing

tape, black electrical tape and regular adhesive tape and observed developed fingerprints

on all three tapes, with minimal background staining. Tape colour proved to be no issue

with this technique as the strong fluorescent property of CdSe under ultra-violet (UV) light

provided sufficient contrast between the fingerprint and background.50

25

2.3.2 Dye Methods

2.3.2.1 Gentian Violet

Gentian violet, also known as crystal violet, is a dye method that results in a dark purple

developed fingerprint.44 The dye works by reacting with the fatty constituents in the

deposited fingerprint, primarily being absorbed by these components and staining the

fingerprint.45 There are two methods by which the dye can be prepared, either dissolving

gentian violet in ethanol (GV-E), or a combination of ethanol and phenol (GV-P), followed by

dilution with water.47 Due to the resultant dark colour of the enhanced fingerprint, poor

contrast on dark adhesive tapes is problematic.6, 45 Developed fingerprints on most surfaces

can potentially be transferred onto fixed photographic paper, but this solution is not

suitable for fingerprints on the adhesive side of tape.45 In a study conducted by Brzozowski

et al.44, both forms of gentian violet solution were tested on different types of brown and

transparent tape that varied in adhesive composition. It was found that the GV-E solution

demonstrated to be an ineffective method for fingerprint development. The best results

achieved with this method was in relation to adhesives with natural rubber, but even this

proved to be the worst method applied in comparison to the other methods conducted in

the study.44 It was also shown to be ineffective in the development of aged fingerprints. In

comparison to this, gentian violet with both ethanol and phenol also demonstrated poor

results, with only slight fingerprint development on fresh deposits, again, only if the

adhesive was made of natural rubber.44

26

2.3.2.2 Ardrox and Liqui-Drox

Ardrox is a fluorescent agent which was initially developed to detect small fractures found

within construction materials.45 Due to its fine composition, Ardrox is able to penetrate and

enter small openings, thus making it a viable option for enhancing ridge patterns in

fingerprints.45, 52 The use of Ardrox involves mixing the reagent with detergent and distilled

water in order to produce a thick, milky-yellow solution.53 The mixture is generally painted

onto the substrate, followed by being rinsed and dried before analysis using UV light.53 This

method has had some successes in developing latent fingerprints on black adhesive tape

due to its fluorescent property; however, it poses some issues with high background

staining, making photography and visualisation difficult.45 Unwanted background

fluorescence can potentially be eliminated using orange or yellow glasses but does not

produce optimum results.52 Scheimer et al.45 argued that Ardrox was not suitable for use on

aged fingerprints and only developed very faint ridge detail on fresh fingerprints. It was also

demonstrated that fingerprints developed with this method significantly faded within 15

minutes of development, and completely disappeared after 12 hours.45 This was a

significant issue as the method only produced faint fingerprints initially. Alternative

solutions to Ardrox have been developed in an attempt to increase its usability. Liqui-Drox is

a solution composed of Ardrox, Liqui-Nox, and distilled water.52 Much like Adrox solution,

Liqui-Drox is painted onto the surface where it develops for 10 seconds before it is rinsed

until there is no visible stain.53 The developed prints are then examined under a long-wave

UV light, presenting green-yellow fluorescence.52 Despite this method improvement, Rees

and Schwartz54 applied Liqui-Drox to 25 different types of adhesive tape but proved

27

unsuccessful on 11 of the tapes, which included: heavy duty tape, cloth tape, duct tapes of

varying colours, masking tape and transparent packaging tapes.

2.3.2.3 Novel Fluorescent Dyes; HB-7, HB-9, HB-11

Another method of fluorescent dye staining has been proposed by Barros and Valter4, in

order to overcome limitations inherent to gentian violet and other enhancement methods.

The fluorescent dyes (HB-7, HB-9, and HB-11) were developed to combat the issue of

current dyes generally only being successful on light-coloured or transparent tapes.4 Barros,

and Valter4 were able to clearly observe fingerprint ridge detail on transparent tape, brown

tape, black electrical tape and silver duct tape. As these novel fluorescent dyes are still

patent pending, the literature exploring this method is limited.

2.3.2.4 Phase Transfer Catalyst

Phase transfer catalysts (PTC) assist in the interaction between dyes and the chemical

constituents of latent fingerprints.15 Dyes suspended in solutions often have issues with

poor development due to the fact that the dyes are in the aqueous phase, and the

sebaceous components in latent fingerprints are in the organic phase.55 The incorporation

of PTC often resolves the issue of insolubility during the chemical reaction process.55 Jasuja

et al.15 used tetrabutylammonium iodide as the PTC and mixed it with a solution of Rose

Bengal dye, resulting in developed fingerprints on all of the adhesive tapes analysed in the

study. The developed fingerprints resulted in a pink colour, which gave sufficient contrast

between fingerprint and background, except in the case of black electrical tape.15

Visualisation of the developed fingerprints even demonstrated the presence of third level

detail.15 Jasuja et al.55 also evaluated the effectiveness of Rose Bengal-PTC on aged

28

fingerprints, in which, again, all of the tapes utilised responded consistently, much to the

same quality to that of freshly deposited fingerprints. There was an exception in this study,

where aged fingerprints developed on double-sided foam and cloth-based medical tape had

a loss of level three detail.15

2.3.3 Cyanoacrylate Fuming

CA fuming is an age-old technique for developing latent fingerprints. The method involves

the heating of CA within an enclosed chamber, thus causing it to vaporise and circulate

within the chamber.56 During its circulation, the CA vapour comes into contact with the

latent fingerprint and forms a white polymer, known as polycyanoacrylate, along the ridge

detail because of an anionic polymerization reaction.57 As CA fuming essentially fixes the

fingerprints to the substrate, subsequent analysis is able to be carried out without risking

the loss of the fingerprint.49 Sock et al.6 examined the effectiveness of latent fingerprints

developed by CA fuming and resulted in successes on both transparent and black electrical

tape. With regards to these substrates, the white polymerisation created a good contrast

between the developed fingerprint and the background; however, when the technique was

applied to masking tape, any possible detail failed to be observed, despite a latent

fingerprint being deposited.6 This result was also observed in a study conducted by

Matthias58. CA fuming is almost always coupled with a powder or dye method to enhance

the developed fingerprint further.45 Olenik59 proposed using Basic Yellow-40 dye alone

following CA to further enhance the developed fingerprints on duct tape and had successful

results, but observed some noticeable background staining. Wilson60 utilised CA fuming with

gentian violet, alternate black powder and a mixture of Rhodamine 6G (R6G), Ardrox, and

Basic Yellow-40 (RAY dye) in attempt to increase visualisation of the latent fingerprints.

29

Tapes to be tested were separated into two groups of CA fuming in which Group 1 was

followed by subsequent analysis using gentian violet, alternate black powder (or white

powder for black electrical tape) and, finally, RAY dye, whereas Group 2 was followed with

RAY dye only. Analysis of fingerprints from Group 1 showed level one detail after treatment

with gentian violet and worked best on the black and brown tapes. Following the addition of

alternate powder, detail decreased with little to no development able to be observed. RAY

dye application increased the detail of developed fingerprints with the majority exhibiting

many visible minutiae. Group 2 results only exhibited detail of some minutiae and gave little

to no development on packaging and duct tapes. In a study conducted by Scheimer et al.45,

the use of R6G or a combination of Basic Yellow-40 and Basic Red-28 (BY40/BR28) was used

to further enhance CA developed fingerprints. It was apparent that BY40/BR28 treated

fingerprints gave off a brighter fluorescence in comparison to those treated with R6G. The

selectiveness of R6G to the fingerprint was also less than BY40/BR28 and had a tendency to

stain the background.45 With regards to aged fingerprints, CA fuming was proved successful,

but as the age of fingerprint increased, the more time was required for the fuming process.

2.3.4 One-step Cyanoacrylate Fuming

The development of one-step CA fuming was intended to fundamentally incorporate the

dye method into the CA fuming method.61 Attempts of this integration have started since

the 1980s and, since then, several commercially available products such as PolyCyano UV

(Foster and Freeman Ltd.), PECA Multiband (BVDA) and Lumicyano™ (Crime Scene

Technology) have been marketed.62 PolyCyano UV was evaluated by Hahn and

Ramotowski63 and resulted in the product being comparable with conventional CA fuming.

Farrugia et al.62 argued that one-step CA fuming produced a noticeable advantage in

30

comparison to the other methods tested, in relation to background fluorescence reduction.

Hahn and Ramotowski63 also noted that, much like traditional CA fuming, PolyCyano UV

effectiveness was very dependent on the substrate it was applied to. Chadwick et al.64

stated that an advantage of one-step fuming methods was that they are more efficient and

minimised hazardous chemical use. It also demonstrated to be superior in the sense that it

can be applied to semi-porous and porous surfaces, which most conventional stains cannot.

Khuu et al.61 evaluated several one-step fuming methods, including PolyCyano UV, PECA

Multiband, and Lumicyano™, in which these techniques showed better results on

polystyrene in comparison to traditional CA fuming. It was also found that one-step CA

fuming has the potential to produce superior results on aged fingerprints when compared

to traditional CA fuming. Various studies61, 63, 64 noted that despite the successes with one-

step fuming processes, the high heating temperatures involved requires the modification of

existing fuming cabinets and, as such, cyanoacrylates exposed to high temperatures could

potentially produce toxic hydrogen cyanide gas. It should be taken into account that the

previously discussed one-step CA studies were not applied to developing latent fingerprint

on the adhesive side of tapes. At this time, no published research has been available on the

application of PolyCyano UV and PECA multiband on the adhesive side of tape. A recent

study by Chung65 applied Lumicyano™ to varying dark-coloured adhesive tapes and yielded

successful results comparable to traditional CA fuming. The study did, however,

demonstrate an issue with developing latent fingerprints on tapes with rubber-based

adhesives, but did not state whether the rubber was natural or synthetic. In addition to this,

the study solely focused on dark-coloured tapes, therefore excluding other types of tape.65

Regardless of the increased cost of one-step CA fuming in comparison to other techniques,

31

the cost of time would be greatly reduced, and the need for subsequent analysis materials

would be made redundant.63

2.4 Comparison of Enhancement Techniques

Scheimer et al.45 found the sticky-side powder to be less effective than gentian violet, and

BPS on black electrical tape in which the ridges developed were too faint to enable

adequate analysis even when transferred onto fixed photographic paper, and were much

too dark to give adequate contrast on the tape alone. Hollars et al.52 and Rees and

Schwartz54 both argued that sticky-side powder was inferior in comparison to gentian violet

and Liqui-Drox on black electrical tape, and Liqui-Drox on orange transparent tape. In

contrast to this, Brzozowski et al.44 recommended sticky-side powder for the use on

adhesive tape with rubber-based glues, but not for acrylate-based glues. Additionally, the

sticky-side powder was observably more efficient than gentian violet when used to develop

aged fingerprints.44

BPS were found to be superior when compared to sticky-side powder and developed

intense visual marks.45 When analysed alongside gentian violet, results were comparable.45

Rees and Schwartz54 found BPS to be a better method of enhancement to Liqui-Drox when

developing latent fingerprints on grey duct tape. BPS also demonstrated quality fingerprints

on yellow, green, and red transparent tapes. In addition to this, fingerprints developed on

light brown packaging tape was higher in quality using BPS in comparison to Liqui-Drox.

Alternatively, Jasuja et al.15 had issues with BPS showing considerable amounts of

background staining on all adhesive tapes tested.

32

Scheimer et al.45 detailed WPS to be comparable to CA fuming, but more superior in

comparison to a physical developer and Ardrox, developing even depleted fingerprints as

well as strong fingerprints. Background staining was occasionally observed, but was minimal

and could potentially be reduced by limiting the number of coats of the suspension or

decreasing the development time.45 Brzozowski et al.44 concurred with these findings and

concluded that WPS was the most efficient agent, especially in relation to most aged

fingerprints. Bleay et al.47 recommended that WPS only be applied to dark-coloured tapes

that had been wetted.

Physical developer was observed to be an ineffective method of development on the

adhesive side of tape. Sodhi and Kaur13 raised the issues of physical developer being

expensive, destructive, time-consuming, and requiring pre and post treatments. Scheimer et

al.45 observed high background staining and stated that if the powder was more selective to

the fingerprint, increased quality of contrast would have been apparent. Additionally,

physical developer was inferior when compared to WPS and CA fuming. Results were

comparable, though potentially worse than the poorly developed fingerprints by Ardrox. In

an attempt to enhance the development method, more coats of the developer were

applied, as well as increased development time, but proved only to create more background

staining and no fingerprint development.45

SPR was less effective than gentian violet, and BPS, as the ridge detail developed, was too

faint to enable analysis.45 It was also observed to be prone to background staining.50 An

issue with the use of SPR is the requirement of a surfactant, which is generally a synthetic

detergent, sometimes containing harmful organic compounds.17 There is limited literature

on the use of SPR on the adhesive side of tape, so its comparison to other development

33

methods cannot be commented on extensively. This is the case for CdSe nanoparticle

reagent, but it was found to demonstrate less background staining and improved contrast in

comparison to TiO2 SPR and gentian violet.51

Studies showed gentian violet to be a more superior method to sticky-side powder and SPR,

but comparable to BPS, except in the case of aged fingerprints.45, 47 Jasuja et al.15 stated that

gentian violet gave better results on non-porous tapes as it would develop extensive

background staining on porous tapes. Alternatively, when compared to Liqui-Drox and novel

fluorescent dyes, it was less effective in development due to the background staining.4, 52

The main issue with the use of gentian violet is that it is an irritant to the skin and eyes, and

some studies have tried to determine whether it has carcinogenic properties.66

Scheimer et al.45 found Ardrox to be unsuitable for aged fingerprints, but developed fresh

fingerprints, despite being faint in nature. Hollars et al.52 found Liqui-Drox to be a more

superior method on black adhesive tape when compared to sticky-side powder and gentian

violet, only if the tape is not damaged by excessive heat or environmental conditions.

Results were comparable with BPS, with the exception of grey duct tape in which BPS

developed higher quality fingerprints. It yielded high-quality fingerprints on brown

packaging tape and blue transparent packaging tape and outperformed BPS on dark brown

packaging tape. With regards to orange transparent tape, Liqui-Drox was more effective

than sticky-side powder, and on cloudy scotch tape, it was found to be superior in

development in comparison with gentian violet.52

With limited studies conducted on novel fluorescent dyes, this method was only compared

to gentian violet, in which the proposed developed dyes gave stronger fluorescence, as well

as better contrast and excellent ridge detail quality on transparent tape, brown packaging

34

tape, black electrical tape and grey duct tape.4 As these dyes are water soluble, there is no

use of potentially hazardous organic solvents, thus making it a safer alternative.4

The use of PTC tends to have less background staining in comparison to BPS and gentian

violet but proves problematic in the case of fabric adhesive tapes, as with the majority of

dye staining techniques.15 It was also found to be a suitable method for use on aged

fingerprints.15 An advantage to using PTC is that the reagent can potentially have a long

shelf life without interfering with the quality of the developed fingerprints.15 In addition to

this, Jasuja et al.55 observed PTC to be a much more viable and effective method in the case

of substrates that have been submerged, when compared to gentian violet.

CA fuming has repeatedly demonstrated to be the most effective method for the

development of latent fingerprints on the adhesive side of tapes, with very minimal

background staining when fumed in the correct conditions.56, 67 Not only does this method

adequately develop latent fingerprints, but also does not interfere with subsequent DNA

analysis as some fingerprint powders and dyes do.56 Scheimer et al.45 indicated that

developing fingerprints on the adhesive side of black electrical tape was most successful

using CA, being effective on both fresh and aged fingerprints. With regards to the 5 different

types of black electrical tape used in the study, CA fuming was not only able to develop

prints on all types, but also on both sides of the adhesive tape. Despite results of CA fuming

being comparable to WPS, it should be noted that the two types of methods are mutually

exclusive; i.e., if one is applied, the other cannot be used in succession.45 This provides an

advantage of using CA over WPS as fingerprints developed by CA fuming can be treated in

succession using other techniques, such as dyes, without risking the loss of detail.56 The

main advantage to using CA fuming over other methods is that it is probably the cheapest

35

technique to use, without sacrificing the quality of enhancements.63 There is, however, risk

of overdevelopment of the fingerprint which is irreversible, henceforth the technique

requires constant monitoring.56 The amount of humidity within the fuming chamber also

needs to be taken into account as humidity in CA fuming greatly influences the eccrine

constituents more than the sebaceous constituents in latent fingerprints.67 Studies

conducted have stated that the optimum humidity level to enable the most efficient CA

fuming is approximately 80%, in which humidity levels lower or higher than this value will

greatly affect the ridge detail observed due to polymer formation.68, 69

3. EXPERIMENTAL AIMS AND OBJECTIVES

The purpose of this study will be to overcome common issues associated with current

methods of latent fingerprint enhancement, with regards to the adhesive side of tape. As a

result of its sticky-nature and surface composition, such issues include the high potential of

background staining, lack of enhancement or difficulty in visualisation, possible detail and

DNA loss, and tedious processing. For the purpose of this research, the application of

several one-step CA fuming processes will be assessed in comparison to traditional CA

fuming and staining with RG6 dye. The one-step CA fuming reagents to be utilised in this

study will be PolyCyano UV (Foster and Freeman Ltd.) and Lumicyano™ (Crime Scene

Technology). These reagents will be applied to various compositions of adhesive tape

including, but not limited to, clear sticky tape, brown packaging tape, white masking tape,

black electrical tape and grey duct tape. Therefore, this study aims to evaluate the efficiency

of one-step fuming methods on latent fingerprints on the adhesive side of tape by achieving

the following objectives:

36

Assess the ability to detect and enhance latent fingerprints on the adhesive side of

tape using traditional CA fuming and enhancement with R6G.


tape using one-step CA fuming methods.


tapes with varying material and adhesive compositions.

Assess the ability to detect and enhance aged latent fingerprints on the adhesive

side of tape using traditional CA fuming and one-step CA fuming.

Assess the sensitivity of detection of latent fingerprints on the adhesive side of tape

using various CA fuming methods.

4. CONCLUSION

Latent fingerprint detection and enhancement methods have continued to develop and

adapt to the various types of surfaces that are presented in forensic investigations. From the

examined literature, sticky-side powder, SPR, and physical developer demonstrated to be

the most ineffective methods of enhancement. With regards to light-coloured adhesive

tapes, BPS, gentian violet, and PTC performed the best but still often posed issues with

background staining due to the dark coloured deposits developed. In relation to dark-

coloured adhesives, Ardrox/Liqui-Drox and novel fluorescent dyes were advantageous in

comparison to other methods owing to their fluorescent properties. Though WPS were also

found to be effective on dark-coloured adhesives, it was recommended that they are only

used in the case of wetted substrates. When tested on their effectiveness on aged or

depleted fingerprints, sticky-side powder, PTC and WPS gave the best results. CA fuming

37

was the only method that performed well in all of these cases. It was observed to produce

detailed fingerprints on most colours of adhesive tape, as well as sufficient detail on aged or

depleted fingerprints. CA fuming only gave background staining when the development time

of the technique was used in excess. In addition to this, CA fuming does not require pre-

treatment processes and can often be used alone without post-treatment dyes or powders,

especially with regards to darker-coloured adhesives. The use of developed one-step CA

fuming methods removes the need for the application of potentially hazardous dyes and

reduces the total development time of fingerprints. It has been proven to produce quality

fingerprints comparable with traditional CA fuming, but with a reduced amount of steps.

Research into the application of one-step fuming methods to the development of latent

fingerprints on the adhesive side of tape could potentially reduce the amount of time to

analyse fingerprints, thus providing faster results with the same, if not better, quality of

detail. It can also prove to be a safer method of development and require fewer elements

and chemicals during analysis.

38

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62. Farrugia KJ, Farrugia KJ, Deacon P, Fraser J. Evaluation of Lumicyano™ cyanoacrylate

fuming process for the development of latent fingermarks on plastic carrier bags by means

of a pseudo operational comparative trial. Science & justice. 2014;54(2):126-32.

63. Hahn W, Ramotowski R. Evaluation of a Novel One-Step Fluorescent Cyanoacrylate

Fuming Process for Latent Print Visualization. Journal of Forensic Identification.

2012;62(3):279-98.

64. Chadwick S, Chadwick S, Xiao L, Maynard P, Lennard C. PolyCyano UV: an

investigation into a one-step luminescent cyanoacrylate fuming process. Australian journal

of forensic sciences. 2014;46(4):471-84.

65. Chung AYY. The detection and enhancement of latent fingerprints present on the

adhesive side of black or dark coloured adhesive tapes. Perth, Western Australia: Murdoch

University; 2018.

66. Rosenkranz HS, Carr HS. Possible Hazard In Use Of Gentian Violet. The British

Medical Journal. 1971;3(5776):702-3.

67. Wargacki SP, Lewis LA, Dadmun MD. Understanding the chemistry of the

development of latent fingerprints by superglue fuming. Journal of forensic sciences.

2007;52(5):1057-62.

68. Farrugia KJ, Fraser J, Friel L, Adams D, Attard-Montalto N, Deacon P. A comparison

between atmospheric/humidity and vacuum cyanoacrylate fuming of latent fingermarks.

Forensic Science International (Online). 2015;257:54-70.

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69. Paine M, Bandey HL, Bleay SM, Willson H. The effect of relative humidity on the

effectiveness of the cyanoacrylate fuming process for fingermark development and on the

microstructure of the developed marks. Forensic Science International. 2011;212(1-3):130.

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47

Part Two

Manuscript




OF TAPE

48

ABSTRACT

The detection and identification of fingerprints is critical, as they can provide valuable

information regarding who has been at the crime scene. Adhesive tape is ubiquitous,

therefore, its use in committing a crime is likely. The process of recovering latent

fingerprints on the adhesive side of tapes proves problematic due to the stickiness of the

adhesive. Traditional cyanoacrylate fuming treated with post-development dyes have been

shown to be successful on these substrates; however, use of these dyes can be time

consuming and hazardous. Proposed one-step fuming methods, such as PolyCyano UV and

Lumicyano™ have been successful in developing latent fingerprints on a variety of

substrates, although research for their applicability on the adhesive side of tape is sparse.

This study evaluated the efficiency and quality of PolyCyano UV and Lumicyano™ in

comparison to conventional cyanoacrylate fuming treated with Rhodamine 6G. Lumicyano™

yielded better results in efficiency and quality over varying saturated and aged fingerprints,

compared to the other two methods. Despite PolyCyano UV producing relatively good

results, its fluorescence was weaker, and the development of aged fingerprints was

minimal. Conventional cyanoacrylate fuming was successful in developing fingerprints;

however, the use of Rhodamine 6G dye appeared to degrade some of the tape samples,

thus inhibiting development. Inclusion of longer aging periods and method effect on

subsequent DNA analysis should be explored in future studies to determine the ranging use

of one-step cyanoacrylate fuming methods.

KEYWORDS

One-step cyanoacrylate fuming; Lumicyano™; PolyCyano UV; adhesive tape; latent

fingerprints; Rhodamine 6G

49

Table of Contents

Abstract .......................................................................................................................... 48

Keywords ....................................................................................................................... 48

LIST OF FIGURES ............................................................................................................. 51

LIST OF TABLES ............................................................................................................... 51

LIST OF ABBREVIATIONS ................................................................................................. 52

1. Introduction ................................................................................................................ 53

2. Materials & Methods .................................................................................................. 55

2.1 Fingerprint Samples ............................................................................................. 55

2.2 Fuming Conditions ............................................................................................... 56

2.2.1 Chamber Set-Up ................................................................................... 56

2.2.2 Fuming Process ..................................................................................... 56

2.2.3 Post-development ................................................................................ 57

2.3 Visualisation ......................................................................................................... 57

2.4 Classification/Reporting of Results ...................................................................... 58

3. Results/Discussion ...................................................................................................... 58

3.1 Sample Visualisation ............................................................................................ 58

3.1.1 Visualisation Under White Light ........................................................... 58

3.1.2 Visualisation Under Alternative Light Sources ...................................... 59

3.1.3 Visualisation On Substrate Surface ....................................................... 61

3.2 Method Evaluation ............................................................................................. 61

3.3 Sensitivity Analysis ............................................................................................... 62

3.4 Aged Sample Analysis .......................................................................................... 64

3.5 Substrate Type Evaluation ................................................................................... 67

4. Conclusion .................................................................................................................. 68

5. References .................................................................................................................. 71

50

6. APPENDIX .................................................................................................................. . 75

51

LIST OF FIGURES

Figure 1 PolyCyano UV developed fingerprint under: a) white light; b) UV light .........60

Figure 2 Total quality analysis of Cyanoacrylate + R6G, Lumicyano™ and PolyCyano UV

treated fingerprints ....................................................................................... 62

Figure 3 Sensitivity quality of Cyanoacrylate + R6G, Lumicyano™ and PolyCyano UV

treated fingerprints exhibiting: a) Level 1 detail; b) Level 2 detail; c) Level 3

detail .............................................................................................................. 64

Figure 4 Quality of aged fingerprints exhibiting level 1, level 2 and level 3 detail using:

a) Cyanoacrylate + R6G; b) Lumicyano™; c) PolyCyano UV ........................... 66

LIST OF TABLES

Table 1 Dosage summary of fuming conditions ......................................................... 57

Table 2 Bandey Five-Point Scale System .................................................................... 58

Table 3 Total Bandey Scale Percentages .................................................................... 62

Table 4 Sensitivity efficiency of Cyanoacrylate + R6G, Lumicyano™ and PolyCyano UV

treated fingerprints ....................................................................................... 63

Table 5 Efficiency of Cyanoacrylate + R6G, Lumicyano™ and PolyCyano UV on aged

fingerprints .................................................................................................... 65

Table 6 Efficiency of Cyanoacrylate + R6G, Lumicyano™ and PolyCyano UV on acrylic-

based, natural rubber-based and synthetic rubber-based adhesives ........... 68

Appendix 1 List of tape samples used in this study .......................................................... 75

Appendix 2 Photographs of samples after development: a) Immediate; b) 7 days; c) 14

days................................................................................................................ 76

52

LIST OF ABBREVIATIONS

ALS Alternative Light Source

CA Cyanoacrylate

CA + R6G Cyanoacrylate treated with Rhodamine 6G Dye

DMAB p-Dimethyleaminobenzaldehyde

DNA Deoxyribonucleic acid

R6G Rhodamine 6G

RH Relative Humidity

SWGFAST Scientific Working Group on Friction Ridge Analysis, Study and

Technology

53

1. INTRODUCTION

Adhesive tape, acquired at a crime scene, can present multiple types of identifying

evidence, including fibres, hair, deoxyribonucleic acid (DNA) and fingerprints.1-3 The value of

a fingerprint has been utilised as a unique signature to each individual. The probability of

two people, including twins, having identical fingerprint characteristics is unlikely as a result

of the analyses, over multiple levels of detail, involved in fingerprint identification.4, 5 With

regards to the adhesive side of tape, latent fingerprints are likely to be deposited due to

preferred handling without gloves owing to its sticky nature.6 Various optical, physical, and

chemical methods can be utilised to detect and enhance possible fingerprints; however,

most are not suitable for use on the adhesive side of tape.7, 8

Cyanoacrylate (CA) fuming, more commonly known as superglue fuming, is a well-

established method that has proved to be beneficial in ascertaining latent fingerprints on a

variety of surfaces, including the adhesive side of tape.9-12 The heating of liquid CA initiates

its transition into the gaseous phase, that preferentially polymerises on deposited

fingerprint residues.7 This provides vital contrast, necessary for further examination and

analysis.7 However, as a result of the white polymer formed, fingerprints present on lighter-

coloured substrates lack sufficient contrast and often require the use of secondary

techniques.4, 13 Powdering methods can be utilised after CA fuming; however, a dye method

is more suitable for use on adhesive tapes. Rhodamine 6G (RG6) is a highly fluorescent dye

that, when coupled with CA fuming, provides fluorescence of the fingerprint ridges using

alternative light sources (ALS) at specific wavelengths; varying with the solvent used.14

Despite the increased contrast, the addition of organic solvents can have a negative impact

on the developed fingerprint. This limitation leads to the development of one-step CA

fuming.15

54

One-step CA fuming incorporates a fluorescent dye, or fluorophore within the CA fuming

process, that simultaneously develops and enhances the fingerprint.4, 16 PolyCyano UV

(Foster + Freeman Ltd.), unlike liquid superglue, is a solid polymer that contains the

fluorescent compound p-Dimethyleaminobenzaldehyde (DMAB), which varies in

concentrations from 5% up to 15%.17 Takatsu et al.18 reported that DMAB selectively binds

to CA polymers, which could prove beneficial for substrates that are sensitive to organic

solvents involved in two-step processes. Previous studies involving PolyCyano UV have given

results comparable to that of conventional CA fuming, despite quality varying by

substrate.16, 19, 20 However, it has been commonly observed that PolyCyano UV fluorescence

lacks intensity when compared to two-step methods using dyes.16, 19 Unlike conventional CA

fuming, which requires a heating temperature of approximately 120°C, PolyCyano UV

requires 230°C, thus requiring modification of existing fuming chambers.20, 21 Cyanoacrylates

exposed to high temperatures like this pose the risk of producing toxic hydrogen cyanide

gas.22

Lumicyano™ (Crime Science Technology *CST+, France) is one of the newer commercially

available methods. This product involves the combination of a solid powder fluorescent dye

(C4H5CIN4O) and liquid CA.23-25 Much like traditional CA fuming, Lumicyano™ requires a

heating temperature of 120°C , meaning the modification of existing fuming cabinets is not

required.19 Prete et al.26 indicated that Lumicyano™ developed fingerprints with equal or

better ridge detail and sensitivity when compared to CA fuming, and gave excellent contrast

and ridge clarity on various non-porous surfaces. In addition to this, Farrugia et al.21

examined the development of latent fingerprints deposited onto plastic carrier bags using

Lumicyano™ and deemed it a suitable technique for use, even on light coloured substrates.

55

A recent study conducted by Chung27 observed Lumicyano™ to give comparable results to

that of CA fuming when applied to the adhesive side of various dark-coloured duct tapes. As

the adhesive used on tape can vary between manufacturer and tape type, the ability of one-

step CA fuming methods to develop latent fingerprints on different adhesive types should

be investigated.

Though more expensive than conventional CA fuming, one-step fuming has its advantages,

including eliminating the need for a second step. Its effectiveness has been investigated on

various porous, semi-porous and non-porous substrates, with much success, but has had

limited research done on its applicability to the adhesive side of tape.21, 26, 28 Therefore, this

study aims to assess the applicability of PolyCyano UV and Lumicyano™ on the development

of latent fingerprints on the adhesive side of various tapes and evaluate the quality and

performance against conventional CA fuming with a post-treatment using RG6 dye.

Comparisons of the different treatments were analysed according to efficiency, sensitivity,

and ability to develop aged fingerprints on varying adhesive compositions.

2. MATERIALS & METHODS

2.1 Fingerprint Samples

A range of adhesive tapes were obtained for use in this study (Appendix 1). Each adhesive

tape was dispensed sufficiently to ensure a length of approximately 20 cm could be cut from

the middle to avoid latent fingerprints deposited during handling. The non-adhesive side of

each tape was adhered to a transparent acrylate sheet using double sided sticky tape and

repeated once onto nine acrylate sheets. A total of 18 transparent acrylate sheets were

56

used, each with five tape samples adhered to it. Each tape was divided into three areas,

using a marker, to allow adequate spacing of fingerprints.

Hands were thoroughly washed using soap and water and dried prior to depositing

fingerprints. A nominated finger was pressed into a Latent Print Standards Pad (Sirchie®,

North Carolina, United States) using light pressure and three subsequent fingerprints were

deposited onto one tape sample from left to right, producing three prints of varying

saturation; high, medium and low. Between fingerprint deposits on each sample, the finger

was thoroughly cleaned on a new Kimwipes® tissue (Kimberly-Clark Worldwide, Inc.). Tape

samples were separated into three groups; to be developed within 24 hours of the

fingerprints being deposited and after 7 and 14 days of aging. Aged samples were stored in

an enclosed cardboard box and stored at room temperature.

2.2 Fuming Conditions

2.2.1 Chamber Set-Up

An enclosed, 85 L plastic tank was used as a make-shift fuming chamber. The chamber was

cleaned using methanol and allowed to dry completely in a fume hood before each fuming

session. A dual hotplate (Kmart, Australia) was placed inside, and the temperature was

monitored using an infrared thermometer (Generic Infrared Thermometer with Laser

Aimpoint GM-300). A 500 mL beaker with approximately 100 mL water was placed on one

of the hotplate burners to induce humidity into the chamber before fuming.

2.2.2 Fuming Process

Dosages and conditions of each method were adjusted to suit an 85 L tank and are outlined

in Table 1. Fuming reagents were measured into a small, metal baking dish and placed onto

one of the hotplate burners. Samples to be developed were placed into the chamber before

57

turning on the hotplate, allowing the reagent to heat gradually. Samples were monitored

continuously during the fuming process to limit the possibility of over-development. All

samples were fumed for 10 minutes, stopping the fuming process by removing them from

the chamber. Between each fuming method, the hotplate was cooled completely.

Table 1 Dosage summary of fuming conditions

Method Dosage Temperature Required

Cyanoacrylate (CA + R6G) (Loctite® Super Glue 5 g) Rhodamine 6G in 100% methanol (Sigma-Aldrich, St Louis MO, USA)

1 g Liquid Superglue Post-fuming: 1 x 10-5 g/mL R6G

120°C

Lumicyano™ kit LK1-20 (Crime Science Technology, Loos, France)

34 mg Lumicyano Powder™ + 0.8 g Lumicyano Solution™

120°C

PolyCyano UV 10 g (Foster + Freeman Ltd.)

0.268 g PolyCyano UV Powder 230°C

2.2.3 Post-development

Samples developed with CA were dyed with R6G for approximately 10 seconds by spraying

the dye onto the tapes before rinsing with methanol and repeating the process. Samples

were placed in a fume hood to dry before analysis.

2.3 Visualisation

Developed fingerprints were photographed using a Nikon D5500 DSLR camera equipped

with a macro lens (AF-S Micro NIKKOR 60mm f/2.8G ED) within 30 minutes after

development. Camera settings were fixed to JPEG Fine (Large 6000x4000). ISO and aperture

were kept consistent at 100 and F11 respectively, while shutter speed was dependent on

the photography conditions. Photographs were not digitally enhanced, but digital image

enhancement software (GNU Image Manipulation Program 2.6.7, GIMP) was used to crop

58

the images to the appropriate size. All fingerprints were photographed under white light.

Additionally, prints were photographed under various Polilight Flare® Plus 2 (Rofin Australia)

depending on the enhancement method; 505nm wavelength for CA + R6G and Lumicyano™,

and 365nm UV light for PolyCyano UV. A HOYA HMC lens (Orange G 62) was coupled with

the macro lens for use with the 505nm Polilight.

2.4 Classification/Reporting of Results

All results were obtained through the examination of the sample photographs and recorded

using Microsoft® Word and Excel. Samples were scored using the Bandey Five-Point Scale

System to determine the efficiency of development; its criteria are described in Table 2.

Sample quality was also assessed based on the presence of first, second and third level

detail, following SWGFAST terminology.29

Table 2 Bandey Five-Point Scale System.30

3. RESULTS & DISCUSSION

3.1 Sample Visualisation

3.1.1 Visualisation Under White Light

Sample images are present in Appendix 2. Under white light, the appearance of all samples

varied between substrates. Fingerprint deposits were most visible on the tapes with darker

coloured adhesive sides (Black PVC, Grey PVC and Brown Packaging tape) showing evidence

GRADE CRITERIA

0 No development

1 No continuous ridges; all discontinuous or dotty

2 One-third of the mark comprised of continuous ridges; the remainder either show no development or dotty

3 Two-thirds of the mark comprised of continuous ridges; the remainder either show no development or dotty

4 Full development; whole mark comprised of continuous ridges

59

of fingerprints without the need for ALS; however, fingerprint deposits on the tapes with

lighter coloured adhesive sides (Clear Packaging Tape, Masking Tape, and Cloth Tapes) were

not as visible to the naked eye. Since the resultant developed fingerprint was white, this

may explain the limited visibility under white light.

3.1.2 Visualisation Under Alternative Light Sources

Samples treated with CA + R6G displayed fluorescence, though it was apparent that some

samples exhibited more fluorescence than others; this could be due to the time allowed for

dyeing. The use of fluorescent dyes on particular surfaces can develop background staining,

making the contrast difficult between the area of interest and the substrate.21 With regards

to this, less time that the dye is in contact with the substrate can result in less background

staining, but as a consequence, less adherence to the developed fingerprint.19 Additionally,

the methanol wash step following dyeing with R6G generally removes excess dye to

decrease potential background staining, however loss of dye adhering to the fingerprint is

also likely.16 The ALS wavelength applied could have been a factor in the reduced

fluorescence observed, as R6G has been tested in various organic solvents to assess

whether its fluorescence was influenced by the solvent selected.14 The R6G in this study was

dissolved in methanol, which was found to have the highest fluorescence intensity, as

observed in a study by Zehentbauer et al.14, though it was also indicated that the underlying

principles of the fluorescence process are not notably influenced by the solvent. It was also

observed that application of the RG6 dye on the tapes with acrylic-based adhesives began to

interact chemically and appeared to separate the adhesive from the polypropylene backing.

This is an issue with a potential loss of fingerprints due to degradation of the tape itself.

60

Lumicyano™ fluorescence allowed optimal contrast between fingerprint and substrate,

particularly with regards to the darker adhesive tapes. Much like samples treated with CA +

R6G, fluorescence varied over different tape samples. The concentration of Lumicyano™

used in this study was an 8% concentration to maximise fluorescence, which was apparent

when examining fingerprints not easily visualised under white light. Beerman et al.4

observed fingerprints fumed with higher concentrations of Lumicyano™ to give greater

fluorescence when compared to lower concentrations of Lumicyano™; however, there was

noticeably more overdevelopment. There was some observable over-development on the

high saturated fingerprints on the smoother adhesive tape substrates, which poses the

question as to whether over-development was a result of high saturation or the method

utilised.

Fluorescence of PolyCyano UV was not as high intensity as Lumicyano™ or CA + R6G, but

utilisation of UV light detected fingerprints that were not visible under white light. Some

grey PVC tape samples did not exhibit fingerprints under white light, yet evidence of a

fingerprint was apparent when observed under UV light (Figure 1). Chadwick et al.16 also

observed PolyCyano UV to give weaker fluorescence compared to CA + R6G developed

fingerprints, but found that subsequent sequencing with R6G gave greater contrast.

Figure 1 PolyCyano UV developed fingerprint under: a) white light; b) UV light

61

3.1.3 Visualisation on Substrate Surface

Fingerprint samples were more easily visible on the tape substrates with smooth adhesive

sides. Due to the flat surface of the PVC and packaging tapes, fingerprints presented more

detailed characteristics in comparison to those deposited on the rough textured cloth tapes.

It was also apparent that more of the overall fingerprint was able to be observed, whereas

the cloth tape fingerprint deposits appeared to only exhibit portions of the print. The higher

sticky quality of the tapes with rubber-based adhesives tended to retain the fingerprint

deposits more than the tapes with acrylic-based adhesives.

3.2 Method Evaluation

Fingerprints were able to be developed on all tape samples except for masking tape.

Samples treated with CA + R6G had the highest percentage of developed fingerprints with a

total of 90.12%; however, the distribution of percentages was relatively even across grades

1—4. Despite Lumicyano™ resulting in around 21% of samples having no development,

33.33% displayed full development with continuous ridge detail, giving the highest result of

complete fingerprints over all methods used. PolyCyano UV was the least successful, with no

development over almost 35% of samples; however, it did give the highest percentage of

samples with two-thirds of development (Table 3).

In terms of quality analysis, samples treated with CA + R6G gave the highest percentage of

level 1 details. Level 2 detail observed for Lumicyano™ was as good as CA + R6G, with

Lumicyano™ proving more superior in relation to level 3 detail. PolyCyano UV gave the

lowest results with less than 31% in all levels of detail (Figure 2).

62

Table 3 Total Bandey Scale Percentages

Figure 2 Total quality analysis of Cyanoacrylate + R6G, Lumicyano™ and PolyCyano UV

treated fingerprints

3.3 Sensitivity Analysis

Sensitivity evaluation demonstrated Lumicyano™ to have results comparable to CA + R6G.

With regards to high saturation deposits, Lumicyano™ performed better than CA + R6G with

48.15% of the sample exhibiting full development with continuous ridge detail. Medium and

low saturated deposits gave similar results between CA + R6G and Lumicyano™; however,

Lumicyano™ performed better in reference to two-thirds development of medium and low

63

saturated fingerprints. In contrast to the comparability of CA + R6G and Lumicyano™,

PolyCyano UV was observed to be less efficient in the case of full development of high

saturated fingerprints; 22.22% and 7.40% less than Lumicyano™ and CA + R6G, respectively.

Medium saturated fingerprints, full development results, were comparable to the low

saturated fingerprints full development results of CA + R6G and Lumicyano™, thus

demonstrating its low sensitivity of detection and development (Table 4). Results from this

study conclude that the sensitivity of CA + R6G and Lumicyano™ are comparable; however,

Lumicyano™ is more likely to result in higher full developed fingerprints on highly saturated

samples.

Table 4 Sensitivity efficiency of Cyanoacrylate + R6G, Lumicyano™, and PolyCyano UV

treated fingerprints

As expected, there was an increased percentage of detail associated with high saturated

fingerprints. CA + R6G treated samples were the most successful in developing fingerprints

that exhibited level 1 detail. Unlike previous results in this study, Lumicyano™ and

PolyCyano UV were similar in results in reference to level 1 detail; however, this pattern did

not continue over level 2 and 3 details. CA + R6G and Lumicyano™, again, were comparable

with regards to level 2 detail, though Lumicyano™ showed higher quality development on

64

low saturated fingerprints. Once again, Lumicyano™ presented the highest percentage of

fingerprints exhibiting level 3 detail across all saturation levels (Figure 3). This reflects its

excellent efficiency; increased complete development increases the likelihood of higher

quality fingerprints. These findings concur with those of Prete et al.26, in which Lumicyano™

was observed to be more sensitive in comparison to conventional CA fuming.

Figure 3 Sensitivity quality of Cyanoacrylate + R6G, Lumicyano™ and PolyCyano UV treated

fingerprints exhibiting: a) Level 1 detail; b) Level 2 detail; c) Level 3 detail

3.4 Aged Samples

The efficiency of each method decreased over time. Samples treated within 24 hours of

fingerprint deposits were more likely to result in detection and development. CA + R6G and

Lumicyano™ performed much the same on aged samples; however, CA + R6G had higher

detection of fingerprints. After 7 days, loss of development was minimal for CA + R6G with

an approximate 50% decrease in full developed samples compared to the 65% and 70%

decrease for Lumicyano™ and PolyCyano UV, respectively. The number of fingerprint

65

samples with no development after 14 days ranged between an increase of approximately

67% for CA + R6G and PolyCyano UV and 77% for Lumicyano™ (Table 5). Beerman et al.4

and Khuu et al.19 suggested that an 8% Lumicyano™ solution is acceptable for fresh

fingerprints, but a 10% solution would be more appropriate for fingerprints 7+ days old; this

could account for the high percentage of fingerprint samples with no development.

Table 5 Efficiency of Cyanoacrylate + R6G, Lumicyano™ and PolyCyano UV on aged

fingerprints

Most fingerprint samples decreased in quality over time. Immediate development observed

CA + R6G and Lumicyano™ to have comparable results with regards to level 1 detail;

however, Lumicyano™ had a higher percentage of level 2 and 3 detail. Following the 7 day

aging period, CA + R6G exhibited more developed fingerprints with both level 1 and 2 detail,

but was still lower than Lumicyano™ in developing fingerprints with level 3 detail. After 14

days, it was apparent that CA + R6G still had almost 50% of fingerprints displaying level 1

detail, and had comparable results with Lumicyano™ in exhibiting level 3 detail fingerprints.

66

It was evident that PolyCyano UV did not perform well on aged fingerprints, with only 7.41%

of the sample presenting levels 1—3 detail after 14 days (Figure 4).

Figure 4 Quality of aged fingerprints exhibiting level 1, level 2 and level 3 details using:

a) Cyanoacrylate + R6G; b) Lumicyano™; c) PolyCyano UV

With regards to aged fingerprints, studies have found the degradation of fingerprint details

due to loss of water content. As water constitutes the majority of a latent fingerprint,

evaporation of water over time can increase its susceptibility to decay.13 The aging process,

such as exposure to light, moisture, and heat, have been reported to lead to the

degradation of fingerprints.31 Wargacki et al.13 postulated that the loss of water over time is

a major contributor to susceptibility to decay due to airflow. As a result of this, latent

fingerprint degradation is strongly dependent on moisture. A high amount of water can

cause a less efficient reaction; however, a small amount can help to initiate the

polymerisation process.4 In CA fuming, relative humidity (RH) greatly influences the eccrine

constituents of latent fingerprints, but has shown to be less influential on sebaceous marks.7

Studies have analysed that the optimum RH level for efficient CA fuming is between 75—

80%; where RH above or below this level is more likely to result in poor ridge detail and a

67

decrease in polymer formation.32 Prete et al.26 found that Lumicyano™ was efficient in the

same RH conditions as conventional CA fuming; however, Chadwick et al.16 noted that the

optimal RH level for PolyCyano UV is around 90%, which most existing fuming chambers

cannot reach. This may account for the lack of developed fingerprints using PolyCyano UV in

this study as RH was not monitored.

3.5 Substrate Type

Fingerprint development on different adhesive compositions was variable across the

methods used. With regards to the tapes with acrylic-based adhesives, all methods had

between 30—45% of fingerprints not developing; however, Lumicyano™ was the most

successful with almost 17% displaying full development and continuous ridge detail. This

could be a result of the eliminated need for post-development dyeing, as it was observed

that the R6G solution interfered with tapes that had acrylic-based adhesives. All three

methods were relatively successful in developing fingerprints on tapes with natural rubber-

based adhesives, giving excellent contrast of ridge detail (Appendix 2). CA + R6G gave the

highest percentage of full developed fingerprints on natural rubber-based adhesives,

followed by Lumicyano™ and PolyCyano UV. Fingerprints deposited on synthetic rubber-

based adhesives had less complete development using CA + R6G and PolyCyano UV but had

a very high percentage of approximately 89% using Lumicyano™ (Table 6). A previous study

by Chung27 noted difficulties with developing fingerprints on rubber-based duct tapes using

both CA + R6G fuming and Lumicyano™; however, there were no issues with this in this

study.

68

Table 6 Efficiency of Cyanoacrylate + R6G, Lumicyano™ and PolyCyano UV on acrylic-based,

natural rubber-based and synthetic rubber-based adhesives

4. CONCLUSION

Traditional two-step and emerging one-step fuming techniques can successfully develop

latent fingerprints on the adhesive side of tape. Despite the advantage of its low cost,

conventional CA fuming results were observed to be surpassed by Lumicyano™ in quality.

With regards to a forensic investigation, the quality of a fingerprint is more valuable than

quantity, particularly in terms of identification. Given that all samples throughout the three

methods were developed in a 10-minute time frame, studies evaluating the optimal timing

of these processes with regards to particular substrates should be conducted. For the use on

masking tape, both conventional and one-step CA fuming was found to be unsuccessful, due

to the porosity of the tape; however, Lumicyano™ showed evidence of a fingerprint being

present despite the lack of finer detail. Alternative development methods, such as Ninhydrin

pr sticky-side powder, may be more suitable for application on this type of tape. Although

CA + R6G fuming was more successful in detecting aged fingerprints, the effect of RH on

aged samples deposited onto adhesive tape should be further explored. With regards to the

adhesive used, Lumicyano™ was observed to be the most successful across all the adhesive

69

types tested, making it the most versatile for use on adhesive tapes. Studies assessing the

various methods of tape removal should be evaluated in relation to the use of one-step

fuming methods, to determine if they are still more successful than conventional CA fuming.

Though PolyCyano UV was able to develop fingerprints, its fluorescence and development

on aged samples was less superior to CA + R6G and Lumicyano™. Despite this, the

advantage of one-step fuming methods is that they are compatible with post-treatment

dyes if needed; however, this removes the novelty of having a one-step method.

Additionally, the high heating temperature of PolyCyano UV, posing a risk to the user, as

well as additional costs to modify existing fuming chambers, proves this method to be less

advantageous in comparison to the other two methods. Further studies involving the

optimisation of RH and quantity of PolyCyano UV should be conducted, as the overall cost of

PolyCyano UV does not merit its efficiency.

The fluorescent signal observed on fingerprints developed using Lumicyano™ allows analysis

of sample quality to be carried out immediately. In general, Lumicyano™ proved to be a

simple and effective technique in comparison to the other two methods utilised. There was

no requirement for any dyeing or drying facilities, which substantially cuts down on time

and saves lab space. In addition to this, the use of Lumicyano™ does not require the

utilization of flammable liquids (e.g., methanol) which omits the added costs and hazards

associated with the disposal of these chemicals. As Lumicyano™ operates under the same

conditions as conventional CA fuming (120°C, RH 80%), there is no requirement for

modification of existing equipment previously used with CA fuming. Due to the heating

temperature of Lumicyano™, production of toxic hydrogen cyanide gas is avoided. Studies21,

33 have shown that Lumicyano™ treated fingerprints are less likely to interfere with

70

subsequent DNA analysis, whereas samples treated with post-dyeing procedures tend to

have issues. Current and previous studies have demonstrated that the one-step CA fuming

method, Lumicyano™, has the potential to surpass the use of conventional two-step CA

fuming. As such, further investigation of this method should be conducted.

71

5. REFERENCES

1. Noureddine M, Bailey JA. A Protocol for the Recovery of STR DNA from Fingerprints

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75

6. APPENDIX

Appendix 1: Tape samples used in this study

76

Appendix 2: Photographs of samples after development: a) Immediate; b) 7 days; c) 14 days

a)

Cyanoacrylate + R6G Dye Lumicyano PolyCyano UV

# White Light

505nm

505nm +

Orange Filter

White Light

505nm

505nm +

Orange Filter

White Light

UV

Bla

ck P

VC

Tap

e

1

2

3

Gre

y P

VC

Tap

e

1

2

77

3

Cle

ar P

acka

gin

g Ta

pe

1

2

3

Bro

wn

Pac

kagi

ng

Tap

e

1

2

78

3

Mas

kin

g Ta

pe

1 no

result no result

no result

no result

no result

no result

no result

no result

2 no

result no result

no result

no result

no result

no result

no result

no result

3 no

result no result

no result

no result

no result

no result

no result

no result

Red

Clo

th T

ape

1

2

3

Gre

en C

loth

Tap

e

1

79

2

3

Yel

low

Clo

th T

ape

1

2

3

Bla

ck C

loth

Tap

e

1

80

2

3

Wh

ite

Clo

th T

ape

1

2

3

81

b)


# White Light

505nm

505nm +

Orange Filter

White Light

505nm 505nm + Orange Filter

White Light

UV

Bla

ck P

VC

Tap

e

1

2

3

Gre

y P

VC

Tap

e

1

2

82

3

Cle

ar P

acka

gin

g Ta

pe

1

2

3

Bro

wn

Pac

kagi

ng

Tap

e

1

2

83

3

Mas

kin

g Ta

pe

1 no

result no

result no

result no

result no

result no result

no result

no result

2 no

result no

result no

result no

result no

result no result

no result

no result

3 no

result no

result no

result no

result no

result no result

no result

no result

Red

Clo

th T

ape

1

2

3

Gre

en C

loth

Tap

e

1

84

2

3

Yel

low

Clo

th T

ape

1

2

3

Bla

ck C

loth

Tap

e

1

85

2

3

Wh

ite

Clo

th T

ape

1

2

3

86

c)


# White Light

505nm

505nm +

Orange Filter

White Light

505nm

505nm +

Orange Filter

White Light

UV

Bla

ck P

VC

Tap

e

1

2

3

Gre

y P

VC

Tap

e

1

2

87

3

Cle

ar P

acka

gin

g Ta

pe

1

2

3

Bro

wn

Pac

kagi

ng

Tap

e

1

2

88

3

Mas

kin

g Ta

pe

1 no

result no

result no

result no

result no

result no

result no result no result

2 no

result no

result no

result no

result no

result no


3 no

result no

result no

result no

result no

result no


Red

Clo

th T

ape

1

2

3

Gre

en C

loth

Tap

e

1

89

2

3

Yel

low

Clo

th T

ape

1

2

3

Bla

ck C

loth

Tap

e

1

90

2

3

Wh

ite

Clo

th T

ape

1

2

3

EVALUATING THE EFFICIENCY AND SENSITIVITY OF ONE-STEP ... · detection of latent fingerprints is...

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